Micromachined multi-axis gyroscopes with reduced stress sensitivity
In a general aspect, a micromachined gyroscope can include a substrate and a static mass suspended in an x-y plane over the substrate by a plurality of anchors attached to the substrate. The static mass can be attached to the anchors by anchor suspension flexures. The micromachined gyroscope can include a dynamic mass surrounding the static mass and suspended from the static mass by one or more gyroscope suspension flexures.
1. A micromachined gyroscope comprising:
a substrate;
a static mass suspended in an x-y plane over the substrate;
a dynamic mass surrounding the static mass and suspended from the static mass;
at least one out-of-plane sense electrode disposed on the substrate at an edge of the gyroscope;
at least one in-plane drive electrode; and
at least one in-plane drive sensing electrode, the at least on in-plane drive electrode and the at least one in-plane drive sensing electrode being disposed in a region of the gyroscope closer to a center of the gyroscope than the at least one out-of-plane sense electrode.
2. The micromachined gyroscope of claim 1 , further comprising:
a plurality of anchors coupled with the substrate; and
a plurality of anchor suspension flexures coupling the static mass to the plurality of anchors.
3. The micromachined gyroscope of claim 2 , wherein:
the static mass has an X-shape; and
the plurality of anchors includes a symmetrical arrangement of four anchors, each anchor of the four anchors being attached to the substrate at a same radial distance from a center of the gyroscope.
4. The micromachined gyroscope of claim 3 , wherein the dynamic mass is coupled with the static mass at bottoms of valleys of the X-shape by at least one gyroscope suspension flexure.
5. The micromachined gyroscope of claim 4 , wherein the at least one gyroscope suspension flexure including at least one C-beam flexure.
6. The micromachined gyroscope of claim 2 , wherein the static mass is suspended in the x-y plane over the substrate by a geometrically distributed arrangement of the plurality of anchors.
7. The micromachined gyroscope of claim 6 , wherein the geometrically distributed arrangement of the plurality of anchors is configured to:
track substrate deformation; and
average capacitive gaps between the dynamic mass and out-of-plane rate sense electrodes disposed on the substrate.
8. The micromachined gyroscope of claim 1 , further comprising at least one gyroscope suspension flexure coupling the dynamic mass with the static mass.
9. The micromachined gyroscope of claim 1 , wherein the at least one out-of-plane sense electrode is configured to detect x-axis acceleration and y-axis acceleration of the dynamic mass.
10. The micromachined gyroscope of claim 1 , wherein the at least one in-plane drive electrode and the at least one in-plane drive sensing electrode are coupled with the substrate by respective anchors.
11. The micromachined gyroscope of claim 1 , wherein:
the at least one in-plane drive electrode includes a pair of drive electrodes disposed on a first side of the static mass; and
the at least one in-plane drive sensing electrode includes a pair of drive sensing electrodes disposed on a second side of the static mass, the second side being opposite the first side.
12. The micromachined gyroscope of claim 1 , further comprising at least one in-plane rate sensing electrode.
13. The micromachined gyroscope of claim 12 , wherein the at least one in-plane rate sensing electrode is configured to detect z-axis acceleration of the dynamic mass.
14. The micromachined gyroscope of claim 12 , wherein the at least one in-plane rate sensing electrode includes:
a first z-axis rate sensing electrode disposed on a first side of the static mass; and
a second z-axis rate sensing electrode disposed on a second side of the static mass, the second side being opposite the first side.
15. A micromachined gyroscope comprising:
a substrate;
a static mass suspended in an x-y plane over the substrate;
a dynamic mass surrounding the static mass and suspended from the static mass;
at least one out-of-plane rate sensing electrode disposed on the substrate at an edge of the gyroscope; and
at least one in-plane rate sensing electrode, the at least one in-plane rate sensing electrode being disposed in a region of the gyroscope closer to a center of the gyroscope than the at least one out-of-plane rate sensing electrode.
16. The micromachined gyroscope of claim 15 , wherein the at least one in-plane rate sensing electrode includes:
a first z-axis rate sensing electrode disposed on a first side of the static mass; and
a second z-axis rate sensing electrode disposed on a second side of the static mass, the second side being opposite the first side.
17. The micromachined gyroscope of claim 15 , further comprising:
at least one in-plane drive electrode; and
at least one in-plane drive sensing electrode, the at least one in-plane drive electrode and the at least one in-plane drive sensing electrode being disposed in the region of the gyroscope closer to the center of the gyroscope than the at least one out-of-plane rate sensing electrode.
18. The micromachined gyroscope of claim 17 , wherein:
the at least one in-plane drive electrode includes a pair of drive electrodes disposed on a first side of the static mass; and
the at least one in-plane drive sensing electrode includes a pair of drive sensing electrodes disposed on a second side of the static mass, the second side being opposite the first side.
19. The micromachined gyroscope of claim 15 , wherein the at least one in-plane rate sensing electrode is configured to detect z-axis acceleration of the dynamic mass.
20. The micromachined gyroscope of claim 15 , wherein the at least one out-of-plane rate sensing electrode is configured to detect x-axis acceleration and y-axis acceleration of the dynamic mass.